Apparatus fob computing interest



T. B. HARPER APPARATUS FOR COMPUTING. INTEREST Dec. 6, 4- 1,519,253

Filed April 9, 1923 .4 Sheets-Sheet l T. B. HARPER APPARATUS FORCOMPUTING INTEREST Filed April 9', 1923 4 Sheets-Sheet 2 1'. B. HARPERAPPARATUS FOR COMPUTING INTEREST 4 Sheets-Sheet Filed April 9, 1923 T.B. HARPER APPARATUS FOR COMPUTING INTEREST Filed April 9, 1925 4Sheets-Sheet 4 MmsH-ra'e UNITED S'i siTn and THEODORE B. HARPER, OF

la did series.

F'IAETFORD. CONNECTICUT.

APPARATUS COlVZPUTING INTEREST.

Application filed April 9,

To all whom it may concern:

Be it known that l, Tnnononn B. Hartman, a citizen of the United States,residing at Hartford, in the county of Hartford and State ofConnecticut, have invented a new and useful Improvement in Apparatus forComputing Interest, of which the following is a specification.

Bankers, brokers, accountants, auditor, examiners and others handlinglarge amounts of securities, such as bonds, debentures and notes, in thetransaction of daily business are required to calculate the amount ofinterest due on the securities at different rates for various periods oftime. Books and tables containing compilations at different rates "forvarious periods have been prepared and are customarily used for thispurpose. Owing to the large number of figures in these tables and themanner of reading them extreme care must be exercised to avoid error,and furthermore read' ing these figures is very tiresome to the eyes andbrain of the accountant who has to make a large number of differentcalculations each day.

The object of this invention is to provide a simple mechanical apparatusparticularly designed for such financiers, that is perpetual and can bequickly manipulated by anyone so as to show the exact amount or decimalthereof in dollars and cents, of in terest at any of the usual rates forany lapsed time, which is due on the bonds, notes and similar commercialpapers,only the required figure and the significance thereof orconfirmation of the desired re sult being visible after the correctadjust.- .ment has been effected.

This object is attained by combining a series of rotatable disks havingcalendar day and month notations, interest payment dates, interestrates, figures representing the amount of interest due at differentrates for ditl'erent periods, and windows, arranged in such manner thatstarting from any calendar date to which the apparatus may be set, onturning the handle to the appropriate rate of interest and due date, thewindows will assume such positions that only the lip e showing theamount due for the lapsed time between the paying date and the startingdate, at the particular rate of interest. and the significance thereof.will be exposed to view at the front of the machine. These 1928. SerialIio. 630,720.

disks preferably also have figures represent ing the amounts due onLiberty and Trees ury bonds and notes, which can be n'iade to appear, bysimply turning the handle pointer around directly to the notation of theparticuiar bond it is required to ascertain the interest due thereon.

in the acci'inipanying drawings Fig. l shows a front elevation of anapparatus which embodies the invention. F ig. 2 shows a side elevationof the apparatus. Fig. 3 shows a section oi. the casing and an elevationof one tace of the main disk upon which the interest figures and days ofthe month are placed, only tew, however, of the numerals being depicted.Fig. on larger scale shows a View of a portion of the c asing and thewindow through which the raiding is made. Fig. 5 is a central verticalsection oi the apparatus. Fig. 6 is a view of a portion of the main diskwhich carries the interest figures. Fig. 7 is a view of a portion of oneof the intermediate disks which has small windows tor exposing theinterest numerals and which carries the significance of the figures.Fig.8is a view of a portion of one oi the outer disks which has largewindows tor exposing the interest figures and significance thereof. Fig.i)- is a view of a portion of the casing, near the center, on which arethe interest pa -qment months and rates of interest. Fig. ll) is a viewof the disks and operating knobs look ing from one side. Fig. 11 is aview ot the disks and knobs looking from the other side.

The disks which are manipulated to obtain the desired readings areenclosed in a casing of suitable design mounted on a base 21. In orderthat the apparatus may be made compact and still contain the requiredfigures oi a size easily read, the disks and computations are preferablyarranged so that the calculations at even rates of interest. as 3%, 4:91(3%. 723?. and 8%, will be read. from one side. and the odd rates. as 894, l 70, %i: ii and together with the interestdue on the first, second,third and fourth i and first El i t Liberty bonds and ll/ t Treasurybonds will be read from the other side. For convenience of handlin thecasing is pivoted to the base and anti-ii 'ction bearings 22 areinterposed so that the casing may be quickly turned around to presenteither side to the front. In each face wall of the casing is a radiallylUU formed window 23 of a length and width suificient to expose onecolumn or row oi? radially arranged figures only, and in order tofacilitate the reading of the numerals these windows are closed by amagnifying glass 24.

The main disk is fastened in the casing to a rotatably mounted spindle20 which on the outside of the casing at one end has a handle or turningknob 27 and at the other end a handle or turning knob 28. Fig. 5. On thefaces of the main disk annularly a1 ranged near the outer edge arefigures rep resenting the days of the month. .hese day numerals arelocated so that they will show, one at a time, at the top of the windows2 as does 12 on Fl ll. In the apparatus shown there are but thirty daysrepresented, as that is the number of days per month commonly employedunder stock exchange rules for figuring interest on bonds, etc.

Arranged in columns or radial rows on the faces of the main disk undereach of the days of the month are interest due tigures. Thus this maindisk terms a shiftabie indicia chart or table within tie enclosingcasing. Some of these are shown on Fig. i; and the radial spaces for thesame are indicated on Fig. 3. On one face of the main disk illustratedthe outermost figures oi the columns are the amounts oi? interest on$1000 at for the number oi? days indicated for the columns, less one dayas in common banking practice there is no inter-- est due on the firstday oi all obligations The next inner figures oi the columns a theamounts of interest at 3% for one month plus the days indicated for thecolirnns. The third figures are the amounts or interest at 3% for twomonths plus the days indicated by the numbers at the heads of thecolumns. The fourth figures are the amounts of interest at 23% for threemonths plus the days indicated. The fifth set of figures are the amountsof interest at 3% for i'our inontl plus the days indicated. The sixthfigure in from the periphery are the amounts 2 interest at 3% for fivemonths plus the nun:- her of days indicated at the outer ends oi. thecolumns. The next sets oi? six figures in from the outer ends of thecolumns are the interest on $1000 at l b tor the diii'ereul periods fromone day to months. The third sets of six figures ot' the coliunns thesums at the rate oi? six figures in from the periphery oi" the (l' arethe sums at the rate of (3%. The next sets of six figures are the sumsat the rate of 7%. and the next or innermost set of six figures are thesums at 89. In other words these figures represent the interest onSlli'iti-u at 3. 4, 5, 0, 7 and 8 per cent for all periois from one dayto six months. Six months the limit used on the apparatus shown.

The next oi the interest on bonds and similar commercial iapers lSconnnonly payable semianuually. On the other face oi? the disk arefigures representing the amounts of inter for the rates of El l fl jt,49/ 70 and 5 92) from one day to six months and the interest on Libertybonds. Any one of these 'adial columns of interest figures may bebrought up back oi? the n'iaguiiiyiug window glasses by turning theknobs 27 or 28.

The intern'iediate disks or shutters 22) which stand against and coverthe faces oi the main disk except those portions near the periphei.bearing the day numbers at the heads of t .e columns of interestfigures, are fastened 1o sleeves $30 that are rotatably fitted upon thespindle 2t). Fastened to the outer ends of these sleeves are circularplates which have small windows 32. Fig. 5.

IJL The intermediate disk or shutter on the even interest side oi? thedevice shown has two hundred and sixteen wii'ulows 33 each of a lengthand width that will expose one only oi the interest figures on the maindisk. These windows are located on dii'li'erent radii and Vi! ng(listulic-e. from the center.

Thcri. are six groups of these windows 33 and each group has thirty-sixwindows. The windows of one group are lettered January and July, thenext l eln'uary and Angust the next March and September, the next Apriland October, the next May and hin ember and the last June and December.The windows oi. each group of thirty-six are arranged annulariy instepped series of six. The outer series oi? each six are lettered 3 /7),they are so arranged and stepped that the six numbers of the 3% intcristfigures in the several columns on the main disl: will be successivelyexposed when the intermediate disk or shutter is turned clockwise withrelation to the main indic'a dial or disk. The next inner series of sixwindows are lettered 5W0, as they expose successively the six 4%interest figures. The next series oi six windows are lettered 6%, thenext 7% and the innermost Fig. 10. lly properly turning thisintermediate shutter or disk any one of the interest amounts on the mainindicia disk may he exposed baci: oi the n'iagniiying window in thecasing. all of the other figures being concealed.

The outer shutters or disks 34: which lie over the intermediate disksare fastened to sleeves 115 rotatahlv fitted upon the sleeves S0.lttachcil in the outer ends oi these sleeves 37 are lruohs on. Fig. Theannular plates that are attached to the sleeves 30 and that ha we thwindows 32, cover the faces oi the knobs and on the faces oi. the knobshack oi the windows in the circular plates are the designations Januaryand Jul ,1 Feln'iia and August. March and ftlepteinher April andOctober, May and Noloo vernber, June and December. Fig. 10. Springball-detents 37 are arranged in the knobs so as to engage the plates andnormally retain the knobs and plates in relatively fixed relation, butpermit the knobs to be turned independently to bring the differentmonthly letterings back of the windows 32. In the apparatus illustratedthe relations of the plates and knobs are changed but once a month, theparts being set on the first 0t each month so as to ex pose the presentmonth lettering through the windows 32.

The knobs 36 are also provided with spring plungers 38 which pressagainst serrated faces of collars 39. Fig. 5. These plungers preventdisplacement of the knobs 36 when the knobs 27 and 28 are turned butallow the knobs to be turned when it is desired to turn the intermediateand outer disks. The main disk 25 which is turned by the knobs 27 and28, once a day, is held from displacement when the outer disks areturned, by a ball-detent 4:0 aranged in the casing so as to engage theperiphery of the main disk. Fig. 8. The outer disk 3 on the eveninterest side has thirty-six windows -11 arranged in stepped series ofsix each. Fig. 10. Each of these windows is of a size that will permitthe exposure of six of the inter est figures in the radial columns onthe main disk or exposure of the windows in the intermediate disks insix difierent radial positions. The outermost windows of the series arelocated so as to expose the 3% interest figures for the periods ofJanuary and July, February and August, March and September, April and@ctober, May and November, and June and December. The next inner windowsare arranged to expose the interest ligures tor the several six monthperiods. The next will expose the 5%, the next the 6%, the next the 7%and the innermost the 8% interest figures for the six month terms. Fig.10.

The number of windows in the disks may be Varied according to thecomputations that the device is designed to make in fact in thearrangement illustrated the disks on the Liberty bond side have fewerwindows than the disks on the even interest side.

:knnularly arranged on the casing about the operating knobs back of thewindows Figs. 1 and 5) are graduations representing the various interestrates for each of the six month periods, on one side oi the casing therates noted being for 3, 4, 5, 7 and 8 per cent interest and on theother side the rates being for 3 494%, 4. (7} and 5 72 interest and alsonotations for liberty bonds. Attached to the knobs 36 are pointe l3.Figs. 5 and'lO. Notations for other (a. of bonds may be used in place ofthe l iibeixy bond notations, if desired.

In using this apparatus the knobs 36 and circular plates 31 are adjustedwith relation to each other so that the present month not-ations on thefaces of the knobs will show through the windows 32 in the plates. Thisadjustment is normally made once a month. in the drawings the apparatusis shown as set for the months January and July. The main disk isadjusted, the other disks ren'iaining stationary. until the particularday oi the present calendar month appears at the top of the radialwindow 23 in the easing. This latter setting is normally made each day.The drawing shows the disk set for the twelfth day of the month. Thusthe apparatus is illustrated as set for the twelfth day of January orthe twelt'th day oi July. l -Tith the device set tor the day oi use allthat it is necessary to do to find the amount of interest due on bondsor other papers on that day is to turn the knob 36 until the pointerattached to the knob points to the rate of interest of the bonds on thesection on the casing which is lettered for the months in which theinterest is paid on the bonds. ll'hcn thus turned the amount oi interestdesired to ascertain shows up through the windows. and that amount only.In the drawings the pointer is shown as pointing to 5% payable April andOctober. Setting the plates with relatimi to the knobs for the presentmonth and day brings the small windows in the intermediate disks and thelarge 'idows in the outer disks in such relation that when the knobs areturned to any interest rate for any 1: ayment date the only figure whichwill be exposed through the casing will be that which shows the amountinterest on a thousand dollars ot due at the particular rate from thepayment date to the present day. in the drawings (Figs. 1 and '10) theapparatus is set for the twelfth day of January and July and thecalculation assumed is for a 5%. 9 1000 bond. with coupons payable Apriland (ictober. l i ith this setting the windows are in such relation thatthey show only the figures 14.0277, the interest due on 551000 at 5% onJanuary 12th from October lst or July 12th from .s'tpril 1st. as thecase may be. is previously stated in order to ensure compactness in theapparatus the calculations are for six months rather than a year. asbonds and similar papers are ordinarily payable seininnniiuilly.

On the opposite side of the main disk i i-om that above described. andshown in Fig. 11 are the amounts tor the odd rates oi interest and alsothe interest amounts on Liberty bonds. On this side the apparatus isillustrated as set tor slunving the amount of interest on January orJuly 12th on the third Liberty loan 4 94 bonds which amount is Theinvention is not limited to an ap .atus with the interest amounts readblc on both faces for the figures and shutter .disks can be arranged oneither or both sides of the main disk, as readily understood by thoseskilled in this art.

' By setting this a paratus on the first day of each month for tiepresent month and on each day for the present day, the interest on any$1000 bond may be instantly obtained shown by simply manipulating theknobs and causing the disks to assume such relation that only the amountof interest at the rate and for the period under consideration will beexposed through the casing.

The invention claimed is 1. An apparatus for calculating accruedinterest on bonds comprising a casing having a vision window therein, acalculating.

table having accrued interest. calculations thereon, a disk havingwindows therein of (ill smaller dimension than the vision window in thecasing, a second disk having windows therein of smaller dimension thanthe windows in said first disk, means for setting said disks relativelyfor determining the accrued interest at a. given month, means forshifting the calculating table for positioning the accrued interestamount tor a given day in said month, and means for shifting the diskshaving windows therein and relative to the vision window for exposingthe calculated interest on a bond of a given rate and payable on agivenday.

2. In a calculating apparatus, a casing having a. vision window therein,a calculating table in said casing, a shutter in said casing having aseries or windows therein. adapted to register with the vision window inthe casing, a second shutter in said casing having a series of windowstherein adapted to register with the windows in said first shutter,means for shifting said shut ters to register certain of the openingstherein to permit the view therethrough of desired indicia on saidcalculating table, and means for shifting said calculating table toregister certain indicia thereon with the vision window in said casing.

3. A calculating device comprising an cnclosing casing, provided with anindicia viewing window, an indicia chart mounted therein and havingcolumnar calculations, means for shifting said chart to move an entirecolumn into registry with said window, a first shutter in said casingarranged in front of said chart, said shutter having a series of windowstherein, each of sufficient size to display aggroupments of saidcalculations, means to shift said shutter to said -casing window toselect a desired aggroupment for observation, a second shutter11'l'Stl-1(lCtLS1 I1g interposed between said first shutter and saidchart, said second shutter having aseries of windows therein ofsuflicientsize to display single calculations ofan'aggroupment, andmeans to shift saidsecond'shutter to register a selectedWindow-thereofwith the first shutter window and easing windowwhereby todisplay a desired single calculation.

4. A device for calculating accrued interest onbonds and, the likecomprising an enclosing casing provided with an indicia viewing window,a calculating table mounted in said casing and provided with calculatingindiciav adapted to be viewed through said window, means to shift saidtable to register desired calculations with said Window, a plurality ofoverlyin shutters arranged in said casing between said windowand saidtable to shield said table from view, each of said shutters having aplurality of windowstherein constructed and arranged to register witheach other on movement oi. said shutters into different positions topresent a desired single calculatlon.

5. A device for calculating interest comprising a chart having arrangedthereon columns of interest calculations, the corresponding calculationsof each column differing by increments equal to one day's interest,andeach column including grou s of calculations of variant interestrates, tlie successive calculations of each group differing inincrements corresponding to a months interest of such rate, a casingenclosing'said chart and provided with an in'dicia window-ofsufficient-dimensions to permit the display of an entire single eolmnnof calculations, means for permitting the display. of a selected groupof a selected column, means for permitting the display of a selectedsingle calculation of such selected group,.and.means for. bringing adesired column before said window. i

6. A device for calculating interest comprising a chart having arrangedthereon columns of interestcalculations, the successive calculationsdifi'ering by a predetermined increment and each column including groupsoficorrelated calculations. the successive calculations of which differby predetermined increments, a casing enclosing said chart and providedwith an indicia window of suflicient dimensions to display an entiresingle column, means for shiftably mounting said chart in said casing tobring a desired column of calculations before said window, means forrestrictingthe display of said column to aselectedgroup, and means forrestricting the display of said group to a desired single calculation.

7. A device for calculating interest comprising a dial having radiallyarranged columns of interest calculations, the differential incrementbetween the corresponding calculations in successive coluu'xns being theequivalent of one days accrued inter said dial having a series of daydesignat. g numbers disposed at the marginal head of each of saidcolumns, a casing enclosing said dial and provided with an indi. iawindow oi. su'tlicient length and width to display an entire singleradial column of calculations plus the marginal number therefor, meansfor shittingly mounting said dial in said casing to bring a desiredcolun'in of calculations before saio window, and means interpose';between said dial and said window "for permitting the display of themarginal number and a selected single calculation of the radial columnregistering with said. window.

8. A device for calcinating accrued interest on bonds and the likecomprising an enclosing casing having an elon ated indicia window, adial rotatably mounted therein and provided with radial columns of interest calculations each of a length coextensive with said window, meansfor shitting said dial to bring a selected column in register with saidwindow, a first shutter in said casing between said dial and window andprovided with radially arnnged windows each of a dimension onethirty-sixth of the length of said casing window, a second shutterdisposed between said first shutter and said casing window and providedwith a series of windows each of a length equaling one-sixth of thelength ot' said casing win dew, and means to shift said first and secondshutters to register predetermined windows therein with said casingwindow.

9. A device for calculating accrued inter est on bonds and the likecomprising an enclosing casing having an elongated indicia window, adial rotatably mounted therein and provided with radial columns ofinterest calculations each of a length co-extensive with said window,means for shifting said dial to bring a selected column in register withsaid window, a first shutter in said casing between said dial and windowand pro-- ided with radially arranged windows each of a dimension onethirty-sixth of the length of said casing window, a second shutterdisposed between said first shutter and said cas ing window and providedwith a series of windows each of a length equaling one-sir: h of thelength of said casing window, means to shift said shutters together toregister certain windows therein with said casing window, and means forpermitting the relative shitting of said shutters to register otherwindows in said shutters with each other and with said casing window.

10. A device for calculating accrued in terest on bonds and the likecomprising an. enclosing casing having an elongated indicia window, adial rotatably mounted therein and provided with radial columns ofinterest mlculations, each ot a length co-extensive with said window,means for shifting said dial to bring a selected column in 7 or withsaid window, a first shutter in said casin between said dial and windowand provi red with radially arranged windows each of a dimension onethirtvsixth ot the length 0t said casing window, a ond shutter disposedbetween said first shut ter and second casing window and provided with aseries of windows each of a length equally one-sixth of the length ofsaid casing window, and means to shift said first and second shutters toregister predeter' mined windows therein with said casing window.

11. A device for calculating interest com prising an enclosing casinghaving a vision window, a chart shittably mounted in said casin andprovided with interest calcula tions thereon arranged in aggroupmentscorresponding to differentials in daily and also monthly increments ofvariant rates of interest, a plurality of shittable shutters in saidcasing interposed between said chart and vision. window and providedwith windows therein constructed and arranged to permit the presentationbefore said vision window of a single calculation at a timecorresponding to the accrued interest on a predetermined amount at adesired rate and tor a desired iumber of months and days thereof.

12. A. device for calculating accrued interest on bonds and the likecomprising an enclosing casing having an elongated indicia window, aspindle arranged on said casing and having its axis arranged in linewith said window, a dial rotatably mounted on said spindle within saidcasing, said dial having a plurality of columnar calculations radiatingfrom said spindle, each of said columns being of a length coextensivewith said window, a turning knob on said spindle for turning said dial,a plurality of shutters fixedly mounted on said spindle within saidcasing and disposed in over lying relation between said dial and saidcasing window, turning knobs on said spindle each connected to a shutterwhereby on rotation of said knobs said shutters are shifted angularly,means insuring the simultaneous shifting of said shutter knobs. saidmeans being constructed and arranged to permit said knobs to be shiftedrelatively.

13. A device for calculating interest comprising a casing having acentral spindle and an elongated window arranged in the line of axis ofsaid spindle, a dial carried by said spindle within said casing andprovided with radially arranged columns of Hill with said casr a 'windmwtwo in on said spindle outside oi said 3: "n connecting Qltl] mob with ashutter for turning said shut* it an .dieni'ing dial arranged on theoutside rt laid raising; and eonnec ed. with one oi sai l knobs. havinp'indieia thereon ar ang'ed radially ot said spindlin indieia arr edrediail; on

ieuus i T J." i S ilt! llill iii one of said shutter lznohs index on theother shutter lint i pelling both shutter ltnol'is to said means heinn'co ueted and arranged to permit. the EHlililSi'llW'tii oi iii shutterhiiol'is in .,-rtlance with the indicia and index thereon.

141- A device for calculating :iccrr terest on bent and the hire eoniprs enclosing casing;- provided with an elongated indicia viewing window:1 dia rotatahlv mounted in said iasi in and orided with radiallyarranged columns of i interest calculations. means f said dial to hrinany single -adial column into registry i.

icooperative u shitting 7 the indic a window: a first shutter dialdisposed in said easing between said indicating dial and said indieiawindow, said first shutter dial heino; torn'ied with radially disposedwindows therein, a second shutter dial in said casing l'ietween saidfirst shutter dial and sad indicia win dow, said second shutter dialhaving 11 plurality ot radially arranged windo therein, and means torshitting said dials tonether and also relatively in order to hrinf!'ariant coinhinations of said windows into registry with the casingwindovi' and with the calculations on said indicia dial.

15. A device for calculating accrued interest on honds comprising anenclosing ease ing provided with an elongated indicia window, a turningspindle on said casing having its axis in l ne with. said Vindow. anindicia dial on said spindle and within said casing, said dial havingradialh arrziirgml columns of interest calculations thereon, each ofsaid columns being adapted to be brought into registry with said windowon the turnii (it said spindle, a first shutter dial on said spindle inthe cising between said indieia dial and the casing windmv, a secondsluiitter dial on said spindle in said casing between said first shutterdial and id casing winder, an index dial on the tront of said casing);concentrically surrounding; said spindle and provided with i rigidconnection with said second shutter turning knob concentrically sur 1said spindle and on the tront of rez and rigidly connected to said i l.a second turning knob on said spindle contiguous to said first turninglcnolt, said second turning knob beingrigidly rennect ed with raid firstshutter within the singa means for insuring the silnulrotation of saidfirst and second hmi -s said means being constructed and arranged topermit said knobs to turn relatively said lirst shutter dial having); aplurality o't radially arranged coliuuns of windows therein disposed ingroups til about the axis of said shutter all the windows of each otsaid groups predetermined divisions oi u ingr radially arrangedv indiciathereon, said second shutter dial having radially arranged windowsdisposed in Slll'lStfllltlilllY spire-term groups anQularl about theshut 1;. 1L]

16. In it :nlculatingapparatus, a casing having: :1 vision windowtherein, a calculatingi table in said casing, :1 shutter in said casinghaving a series of windows therein .idapted to register with the visionwindow in the casing; 21 second shutter in said cusiup; having a seriesof windows therein adapted to register with the windows in said firstshutter, means constructed and arranged to permit said shutters to heSlii'tted relatively and also together with respect to said visionwindow to permit view of desired calci'ilatin r indiria on said table.and means for Sl'llttl'llfl' said table to register desired indie'athereon with said vision wi n dow.

THEODORE B. HA ll PE R.

